Track drive



March 1, 1949. E. s. MacPHERSON 2,463,040

TRACK DRIVE Filed Aug. 22, 1945 3 Sheets-Sheet l Iinmntor TRACKDRIVEFiled Aug. 22, 1945 3 ShecS-Sheet 2 Inventor A March 1, 1949. E,acPHERsON 2,463,040

TRACK DRIVE Filed Aug. 22, 1945 3 Sheets-Sheet a I ;l V 2% 5 ZhmentorPatented Mar. 1, 1949 TRACK DRIVE Earle S. MacPherson, Detroit, Mich.,assignor to General Motors Corporation, Detroit, Mich., a

corporation of Delaware Application August 22,1945, Serial No. 612,084

Claims.

This invention relates to an improved vehicle Wheel suspension systemfor use especially with endless track installations. Track slack take-updevices usually are essential to insure proper fit necessary to keep thetrack entrained on the wheels against accidental throwoff, especially athigh speeds. High speed requirements dictate reduction in weight and anobject of the present invention is to provide a lightweight sturdy andreliable rocker arm suspension assembly utilizing a load supportingtorsion bar spring to accommodate vertical Wheel deflection.

A further object is to provide an improved lever arm and spring barmounting having adjustable settings suitable for effectin quick and surelongitudinal shifting of the wheel position and in particular the endwheel about which the selflaying track has a return loop.

Additional objects and advantages will appear in the course of thefollowing specification having reference to the accompanying drawingwherein Figure 1 is a side elevation of an endless track vehicle; Figure2 is a transverse vertical sectional view of the endmost road wheel, ason line 22 of Figure 1; Figure 3 is a longitudinal section looking up online 3-3 of Figure 2 and illustrating the adjustable mounting of thelower rocker arm; Figure 4 shows the adjustabl mounting of the upper armand torsional spring bar, as on line 4-4 of Figure 2; Figure 5 is anenlarged detail section of the journal mounting and spring connection ofthe upper rocker arm and Figures 6 and '7 are detail views looking inthe direction of the arrows on lines 6-6 and 'l'l, respectively, ofFigure 4.

In the drawing the reference character I indicates the body or hull ofthe vehicle to be flexibly suspended at either side by a longitudinalsuccession of road wheels 22 and 3, the latter being an end wheel oflarger diameter than the remaining wheels 2-4.. Between the wheels andthe ground is the usual endless self-laying track or band 4 which may bethe conventional articulated shoe type with one end loop entrained aboutthe end wheel 3. In a self-propelled vehicle the other end loop of thetrack is to be engaged with a driving sprocket wheel 5. Idler rollers6-6 support the upper reach of the track. Variable settings of thedistance between end wheel centers enables proper fitting of the trackfor original installation and for subsequent maintenance andcompensation for dimensional changes such as occur due to wear, stretchand service replacements.

As shown in the detail views the end wheel 3 is connected to the hull lby a pair of vertically spaced transverse rocker arms or levers l and 8each pivotally joined on longitudinal axes at opposite ends to the hulll and a forged journal box 9 for the stub shaft and hub ill of the wheel3. A strut or link H. for a shock absorber, not shown, is connected withthe lower arm 8 and a bumper l2 carried by the journal box 9 is arrangedto engage the arm 8 as an abutment stop to limit wheel deflection and asimilar bumper I3 is carried by the upper arm I to engage the journalbox. For convenience the lower arm 8 is forged in two complementaryhalves joined by bolts I4 and each terminates at its inner end in an eyel5 in which is press fitted a bearing sleeve l6 oscillatably mounted ona longitudinally extending shaft I! having supporting brackets I8, I9and 20 fixedly bolted or otherwise secured to the hull l. Theoscillatory bearing surfaces in both of the longitudinally spaced apartjoints are in the nature of helical screw threads and the externallythreaded portions 2l-2I on th shaft are considerably longer than theinternally threaded sleeves IE to enable a wide range of adjustment ofthe interengaging threads. Thus rotation of the shaft, and by reason ofthe screw thread bearings, will enable the rocker arm 8 to be shiftedlongitudinally either backward or forward as required in adjusting theposition of the road wheel.

Longitudinal displacement of the shaft I1 is precluded by the opposingthrust abutment faces at the endmost bearing brackets l8 and 20 engagingshoulders afforded between the threaded shaft portions 2l-2l and thereduced diameter bearing portions 22 rotatably mounted in the respectivebrackets l8 and 2. The shaft I1 is releasably locked about rotation bysplit clamp formations 23 at opposite ends of the center bracket l9engaging with reduced shaft portions 24. When the clamping bolts andnuts are drawn tight the shaft is held rigid but release of the clampswill permit shaft rotation by application of a suitable wrench to thesquared or fiattened shaft terminal 25 projecting beyond the wheelsuspension assembly for easy access. To encase the otherwise exposedshaft threads flexible bellows-like boots 26-26 surround both ends ofthe shaft portions 2l2| and are formed with terminal beads to snap intoannular grooves in the adjoining bearing sleeves and bearing brackets.The boots preferably are of an oil resistant synthetic rubber and keepdirt from reaching the lubricating bearing surfaces.

With the lower arm 8 adjustably mounted on the hull provision is alsomade for change in position of the upper arm 1 with which is associatedthe torsion bar spring 21. A simple arrangement is a clamp bolt andlongitudinal slot connection between the hull and the mounting bracket28 in which the arm 1 is hinged. Four of such bolts 29 are shown:inFigures/1,6 and 7 having their heads welded to upper and lower straps 30inside the hull and with the bolts projecting outwardly through alignedlongitudia nally elongated slots in the internal stifiener plate 3|, thehull'body and the mounting flanges V of the bracket 28 and receivinexternal-nuts for.

removably clamping the parts; A removable inspection plate or door 32 isdesirably used to seal the bolt receiving openingsthrough :thehulL;

The hinged mounting of the upper arm 'Iis by means of two sets of rollerbearings 33'-'33 spaced on opposite sides, of the arm and interposedbetween cylindrical portions of the bracket and a tubular part 34-keyed to the arm 1 and sleevedon the adjacent end of the spring-bar. 21.serrations or splines 35 key the sleeve to the spring bar or torsionalrod. 21 and the sleeve is secured: by its abutment at one end with anenlarged shoulder on the, bar endby a clamping washer 36 held againstthe opposite sleeve end by afastening nut 31. One end; of the hollowbracket is closedby a threaded plug 38 and the other: endis closed by aseallngring orygasket 39,.engaging, the: relatively rotatable torsionbar at therocker anm end thereof.

The, opposite end of the torsion bar 21:11eeds to be fixed so that itsintermediate portion can be twisted; incident to its elastic suspensionof 'the'load, the length of the bar between the oscillatory arm and thenonrotative anchorage beingdetermined by the-characteristics of the barin relation to the-load to be supported. For a nonrotational anchorageof the fixed end it is proposed. to provide the bar with an externallysplined portion it having aslip fit-with an internally splined bracket4| bolted to thehull. Beyond: the. splined portion 48 the bar terminatesina reduced diameter threaded tip 42. extending through an eye orapertured bracket 43 bolted to thehull and having jamnuts 44-44 threadedthereon to be drawn, tightly against the opposite faces of the eye 43for locking the spring bar against longitudinal displacement except whenthe nuts 44 are turned back to allow slippage of the splined portionsmland 4! in accommodating relocation of the rocker arm supporting bracket28:,as wheel setting is varied.

, I claim:

7 1. In, an endless track assembly, an endless drive track, a tracktake-up wheel about which said track, is looped, a suspension, arm forthe wheel,,a mounting shaft having threaded bearing engagement with thearm and, extending longi. tudinally of said track and means to impartrelative rotation to the shaft and arm to cause by reasonof saidthreaded bearing engagement-a longitudinal shifting of the wheel inaccordance with-track length.

2., In, combination, an endless drive loop, a wheel over which the loopis entrained, a wheel supporting a rockable arm journaledonan axisextending substantially longitudinally of the loop for enabling wheeldeflection in a plane transverse tothe loopv length, and -a.rotatablyadjustable mounting shaft havingthreaded bearing engagementwith thearmto accommodate rock-- ing movement of the arm and the longitudinal 4positioning of the wheel upon rotatable adjustment of the mountingshaft.

3. In an endless track vehicle, a track loop, a suspension wheel havinga loop end entrained thereon, a wheel supporting rocker armaccommodating wheel deflection, a rotatably adjustable shaft mountingsaid arm on an axis extending longitudinally of: the vehicle, andinterengaging screw threaded hearings on the shaft and arm for causinglongitudinal travel of the arm upon shaft rotation.

4. In an endless track vehicle having a supporting wheel over which atrack end loop runs, alwheelzsuspension. rocker arm, a rotatablyadjustable shaft for mounting the arm on a longitudinal axis and havingscrew threaded bearing engagement'withthe arm, means to support theshaft for rotation and against longitudinal travel and means toreleasably clamp the shaft against rotation.

5; In an endless trackv vehicle. having a. supportingwheel over which atrack end loop runs, a. wheel suspension rocker arm, a rotatablyadjustablei, shaft for mounting thearm ona longitudinal axis and havingscrew threaded bearing engagement With'the arm,. means to support theshaftforrotation' and against longitudinal travel and means toreleasably clam the shaftagainst rotation, a second wheel suspensionrocker arm in spaced parallelism to the first and. a torsion spring baroperatively connected with said second wheel suspension rocker arm.

6-.JIn an endless track vehicle having a .supporting wheel over which atrack end loop'runs, apair: of substantially parallel wheel suspensionrocker arms, eachpivot-ally joined at its opposite ends to the vehicleand to the wheel, respectively, a torsion bar loadsupporting: springoperatively connectedxto one end of one. of the rocker arms, adjustablemeans associated with an end of the other rocker arm to enable the wheelto be positioned-longitudinally of the track to compensate for trackslack and a fixed anchorage bracket sli-dably and nonrotatively engagedwith the spring torsion bar to take the reaction thereof and accommodatewheel position change upon adjustment of said means.

'7'. A' wheel suspension for vehicles, including a pair of spaced rockerarms, adjustable means mountingboth arms for selective longitudinalpositioning in various relative settings, a torsion barspringoperatively connected at one end to one of said arms and a fixedanchorage support for the other end of the torsion bar spring andengaging the same with a nonrotative slip fit to accommodate theadjustment settings of said arms.

8. In a: vehicle wheel suspension system, a transverse rocker arm, alongitudinally adjustable bracket pivotally mounting said arm on alongitudinal-axis, a longitudinally extending load supporting torsionspring bar secured at one end to said arm, andsupporting means slidablyand nonrotatabl y engaging the torsion bar near its opposite end.

9. In a vehicle wheel suspension system, a rocker arm, a supportingbracket in which said arm is journaled, a pin and slot mounting for saidbracketto enable the same-to be'shiftedaxially of the journal toselectedsettings, a torsion spring bar-having one end joined to said arm, anaxially adjustable support for the opposite end of the torsionspring'bar forcooperation with said pin and slot mountingand-springreaction anchorage device engaging the torsion spring bar near said last-mentioned end with a "nonrotative =sl-i'p fit.

10. Suspension means between a vehicle and a road wheel, including arocker arm having pivotal connection at one end with the road wheel andhaving at its opposite end a pair of axially spaced bearing eyes, eachformed with internal helical bearing threads, a supporting journal shaftprojecting through both eyes and having external helical bearing threadsin engagement with said internal bearing threads of both eyes, vehiclecarried meansjournaling said shaft for rotation, interengaging shoulderson the shaft and said journal means to prevent axial travel of the shaftupon its rotation and to compel axial travel of the eyes through theirthreaded engagement with EARLE S. MACPHERSON.

REFERENCES CITED The following references are of record inithe file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,947,475 Knox et a1 Feb. 20,1934 2,255,088 Shroeter Sept. 9, 1941

